NASHVILLE, Tenn. (AP) — A U.S. Army lieutenant colonel was arrested Thursday on charges that he illegally imported firearms parts from foreign countries including Russia and dealt weapons without a license, federal prosecutors said.

Frank Ross Talbert, 40, has been indicted on 21 charges including importing defense articles without a license, smuggling firearms parts into the U.S., firearms trafficking, possession of unregistered machine guns, transporting a machine gun without a license and dealing in firearms without a license, the U.S. attorney’s office in Nashville said in a news release.

Talbert pleaded not guilty during a Thursday hearing in federal court in Nashville, records showed. He was released from custody on certain conditions, including that he submit to supervision by a court officer, surrender his passport and restrict his travel only to Tennessee and Fort Campbell, Kentucky, records showed.

Talbert, a lieutenant colonel with the Army’s Explosives Ordinance Disposal at Fort Campbell, was arrested after federal law enforcement agents executed multiple search warrants during their investigation, prosecutors said.

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The indictment said Talbert illegally imported parts for AK-style firearms without the proper license and authorization, in violation of the Arms Export Control Act. The parts include pistol grips, hand guards, buttstocks, sights, gas tubes and muzzle devices, the indictment said.

Talbert was also accused of illegally importing 55 inert rifle grenades, illegally possessing AK-47 machine guns, and illegally selling a partially destroyed AK-47 kit, which prosecutors said was transported from Tennessee to Kentucky.

The imported parts came from Russia, Germany, Poland and the Czech Republic, the indictment said. If convicted, Talbert faces a maximum sentence of 20 years in prison.

Fort Campbell is a sprawling base that straddles the Kentucky-Tennessee line, about 60 miles (97 kilometers) northwest of Nashville.